Production of artificial filaments, yarns, threads and the like



p 26, 1951 J. H. GIVENS ETAL 3,001,851

PRODUCTION OF ARTIFICIAL FILAMENTS, YARNS, THREADS AND THE LIKE Filed June 27, 1958 2 Sheets-Sheet 1 F/G. MI

WWW IHII llll \Illlllllllif' \[\"IfllilllllllllllllllIll v 5 8d 6 ANGUL/U? SPEED 07 30/70'4 .9 same D/AMETERSofO/SCS on 3and4 dlfferenf Jam Harr/son 6/1/6/73 Harry Rona/d Hardy Daw'd/Wcho/son MW By lhe/r affameys Sept. 26, 1961 J. H. GIVENS ETAL 3,001,851

PRODUCTION OF ARTIFICIAL FILAMENTS, YARNS, THREADS AND THE LIKE Filed June 27, 1958 2 Sheets-Sheet 2 III A/VGULAR SPEED of 3 'ana 4:

d/fferenf D/AMETERS afD/SCS on 3and =same 2 //71/e/7f0r$ John Haw/$00 6/1/6 05 Harry fio/va/dHardy Dav/d Mafia/$00 Ty/er By fhe/r af/omeys MWJM Patented Sept. 26, 1961 3 001 851 PRODUCTION OF ARTIFICIAL FILAMENTS, YARNS, THREADS AND THE LIKE John H. Givens, Harry R. Hardy, and David N. Tyler, Coventry, England, assignors to Courtaulds Limited,

London, England, a British company 1 Filed June 27, 1958, Ser. No. 744,982 Claims priority, application Great Britain July 1,1957

5 Claims. (Cl. 18--54) This invention relates to the production of regenerated cellulose filaments and the like from viscose and particularly to the production of such filaments having a high tenacity and which can be twisted into high strength viscose rayon cords.

The tenacity of regenerated cellulose filaments can be increased by subjecting them immediately after spinning to stretching in a hot dilute acid bath as described in British patent specification No. 467,500. The addition to the viscose of certain compounds enables filaments to be produced having a thick skin and in some instances a noncrenulated surface with a bean shaped cross-section. The compounds capable of thus modifying the physical characteristics of the filaments will be referred to in this specification as modifiers. Among the compounds which have been proposed for use as modifiers are quaternary ammonium compounds, amines, dithiocarbonates, aryl thioureas, thioglycol, polyethylene oxide and certain of its derivatives such as the condensation products of an amine and ethylene oxide. Such modified filaments have a high wet tenacity and are capable of forming a cord of good tensile properties. The skin and core can be shown and the skin and core differentiated by a staining technique as described for example in the Textile Research Journal, 1945, page 443.

We have now found that an advantage in the spinning of viscose containing a modifier is obtained if the stretching of the filaments or a substantial part of it, is carried out in a series of at least five steps instead of in a single large step, successive stretching steps being separated by periods in which the filaments are relaxed and allowed to contract by up to 4 percent of their length.

Each stretching step increases the length of the filaments by from 4 percent to 20 percent, preferably 5 percent to 10 percent and the further stretching of filaments which have already been stretched 50 percent in a series of steps is preferably accomplished when the filaments are wetted with a hot liquid. I

This invention using a series of stretching steps as opposed to a single stretching step allows a greater overall stretch to be imparted to the filaments with the consequent improvement in the tensile properties of the filaments.

When polyethylene oxide is used as the modifier, preferably from 0.5 to 10 percent by weight of thepolyethylene oxide based on the weight of cellulose and having an average molecular weight of between 300 and 10,000 is added to the viscose which is extruded at salt point between 5 and 18 into a bath in which the percentage sulphuric acid is preferably between 0.8 and 1.5 times the percentage of the caustic sodain the viscose and which contains 3 to 20 percent zinc sulphate.

Examples of apparatus which can be used alternately to stretch the filaments and allow them to contract, but which nevertheless impart an overall stretch to the fila ments are shown in the accompanying drawings in which:

FIG. 1 is a diagrammatic representation of a preferred form of apparatus embodying the invention using rollers rotating at the same angular speed.

FIG. 1A is a simplified view of the rollers and yarn of FIG. 1. FIG 1A omits the showing of some of the lengths of yarn in order to avoid confusion. FIG. 1A is a mirror image of FIG. 1, i.e. it is the image which would appear in a mirror set in a plane parallel to the plane determined by the top surfaces of the rollers 1 and 2 as they appear in FIG. 1 and facing in the direction of arrow A in FIG. 1.

FIG. 2 is a diagrammatic representation of a form of apparatus in which the rollers rotate at different angular speeds.

FIG. 2A is a mirror image view, similar to FIG. 1A, of the rollers of FIG. 2 as they would appear in a mirror facing in the direction of the arrow B in FIG. 2A.

Referring to FIGURE 1, stepped rollers 1 and 2 are mounted on spindles 3 and 4 on which are secured identical gear wheels 5 and 6 individually meshed with gear wheel 7 on a driving spindle 8 of a motor 9, so that each roller may be driven in a counter-clockwise direction at the same angular velocity. Stepped roller 1 is composed of peripherally grooved discs A, C, E, G, I, of gradually increasing effective diameters and roller 2 similarly comprises a graduated series of grooved discs B, D, F, H, I. The effective diameter of the groove of each disc is:

A, 2.475 inches; C, 2.673 inches; E, 2.871 inches; G, 3.069 inches; I, 3.267 inches.

B, 2.7 inches; D, 2.9 inches; F, 3.1 inches; H, 3.3 inches; 1, 3.5 inches.

The rollers may have more discs to enable a greater stretch to be imparted to filaments, or two or'more pairs of rollers may be used for the same purpose.

In operation the filaments 10 are wound around the rotating rollers .1 and 2 to follow the path A, B, C, D, E, F, G, H, I, I such that the filaments are in contact with approximately one half of the length of the peripheral groove of any disc. The filaments arethen stretched by 9.1 percent between the discs A and B, contracted by 1 percent between the discs B and C and stretched by 8.5 percent between the discs 0 and D and so on, the filaments being alternately stretched and contracted throughout their residence period on the rollers.

The overall percentage stretch imparted to the filaments may be calculated from the equation:

Overall percentage stretch Diameter of final treatment disc Diameter of initial treatment disc and the stretch or relaxation imparted to the filaments between any two discs is given by the equation:

Percentage stretch or relaxation D ameter of d sc receiv ng filaments X100] 1 00 Diameter of (1180 releasing filaments C; C, D, E; etc,, determine the degree of stretching and contraction that the filaments undergo along the path A, B, C, D, E, and so on and this is also exemplified in the alternative apparatus shown in FIGURE 2 where the rollers turn'in a clockwise direction This is opposite to the direction of FIGS. land 1A because the yarns are wound around the rollers in the opposite "direction. Identical stepped rollers 11 and 12 move at diiferent angular speeds, roller 11 being slightly slower than roller 12 so that the peripheral speeds of discs P, R, T, V, X are less than those of their complementary discs Q, S, U, W, Y,. Filaments wound on the rollers to follow the path P, Q, R, S, T, U,

Percentage stretch or relaxation Peripheral speed of disc receiving filaments Peripheral speed of disc releasing filaments Again a negative value indicates a relaxation of the filaments.

The invention is illustrated by the following examples in which all percentages are by weight. In Examples 1 to 4 viscose containing 7.5 percent of cellulose, 7.0 percent of caustic soda and 2 percent based on the weight of the cellulose of polyethylene oxide of average molecular weight 1,500 was extruded at a salt figure of about 10 and a ball fall viscosity of 50 seconds at a final spinning speed of 40 metres per minute into a coagulating and regenerating bath containing 7.3 percent of sulphuric acid, 7.5 percent of zinc sulphate and 14.5 percent of sodium sulphate at 55 C. In Examples 5 and 6 viscose having a ball fall of 180 seconds and containing 6.5 percent cellulose, 7 percent NaOH and 3 percent based on the weight of the cellulose of polyethylene glycol of average molecular weight 1,500 was extruded at a spinning speed of 27 metres a minute into a spinning bath containing 6 percent sulphuric acid, 7.0 percent zinc sulphate and 11.0 percent sodium sulphate at 55 C. In all cases, upon emerging from the spinning bath the filaments were led in eleven 01' more turns round a pair of conical stepped driven rollers, as described above with reference to FIGURE 1, progressing from the smaller to the larger end of each roller and thus being alternately stretched and contracted in a series of steps.

The first part of the stretching was carried out on the rollers in air; the next part on a part of the rollers on which hot water at 50 to 70 C. was sprayed. The final stretch was in one stage in an open hot 3 percent acid bath between the rollers and a further reel or godet. After washing and drying the filaments were twisted into a yarn having an S twist of twelve turns per inch, and two such yarns were doubled with a Z twist of twelve turns per inch to form a cord.

Further details of the processes and the properties of the filaments and cords are given below:

Examples 1 2 3 4 5 6 Total stretch, percent 90 100 110 110 110 120 Air stretch on rollers,

percent 35 50 40 40 23 46 Hot water stretch on rollers, percent 10 18 15 40 44 42 Hot acid stretch, percent 45 32 55 30 43 22 Total relaxation 2. 2 2. 2 2. 2 2. 2 4 6 Yarn denier 1. 664 1, 658 1, 656 1, 662 1, 664 1, 674 Oven dry tenacity, grams] denier 5.05 5. 55 5. 56 5. 72 6. 32 6. 11 Oven dry extensibility,

percent 7. 9 7. 5 8. 5 6. 9 8.0 9. Conditioned tenacity grams/denier (65 percent relative humldity) 4. 31 4. 73 4. 53 4. 87 5. 77 5. 63 Conditioned extensibility 11. 10. 6 11. 5 8. 8 12. 4 12.0 Wet tenacity, grams] denier 3. 19 3. 38 3. 38 3. 38 4. 30 4. 41 Wet extensibility, percent- 24. 5 19. 4 21. 21. 9 26. 5 23. 0 Cord denier 3,860 3, 870 3, 875 3, 875 3, 860 3, 900 Oven dry breaking load,

lb 32. 9 34. 0 34. 3 33. 5 38. 4 38. 5 Oven dry tenacity, grams/ denier 3. 87 4. 00 4. 03 3. 92 4. 51 4. 47 Extensibility, percent.... 13. 8 13. 0 13. 7 11. 0 14. 5 15. 5

It will be seen that the invention has made it possible to stretch viscose filaments by amounts up to percent of their original length and in so doing the all-round tensile properties of the filaments have been improved.

What we claim is:

1. A method for making high tenacity rayon filaments which comprises extruding viscose containing at least 0.5% of a modifier which is capable of producing filaments having a thick skin, from said viscose, into an aqueous acid coagulating bath to form filaments, and immediately stretching the filaments, while they are still wet, in a series of at least five stretching steps, the filaments being stretched from 4% to 20% in each stretching step, there being a relaxing step between each of said stretching steps in which the filaments are permitted to contract by an amount not exceeding 4%, the total stretch imparted to said filaments over said series of stretching and relaxing steps being greater than the stretch imparted by the first of said stretching steps.

2. A process as claimed in claim 1 in which the filaments are stretched by an amount up to 50 percent of their original length in a fluid at ambient temperature and then further stretched when wetted with a hot liquid.

3. A process as claimed in claim 1 in which at least one of the stretching steps increases the length of the filaments by from 5 percent to 10 percent.

4. A process as claimed in claim 1 comprising adding to viscose from 0.5 to 10 percent by weight based on the weight of the cellulose of a polyethylene oxide having an average molecular weight between 300 and 10,000 and extruding the viscose at a salt point between 5 and 18 into an aqueous acid coagulating bath containing sulphuric acid and a percentage equal to from 0.8 to 1.5 times the percentage of caustic soda in the viscose and from 3 to 20 percent of zinc sulphate to form the filaments and immediately thereafter stretching the filaments.

5. A process for making high tenacity rayon filaments which comprises extruding viscose containing at least 0.5 of a modifier which is capable of producing filaments having a thick skin from said viscose, into an aqueous acid coagulating bath to form filaments, withdrawing the filaments from the bath and immediately stretching them, while they are still wet, in a series of at least five stretching steps, the filaments being stretched from 4 to 20% in each step, said stretching being carried out by passing the filaments over a series of at least five positively driven stretching rollers of increasing peripheral speed and over a series of relaxing rollers, there being a relaxing roller between each stretching roller and the next succeeding stretching roller, each of said relaxing rollers having a peripheral speed less than that of the stretching roller immediately preceding it and such that the filaments are permitted to contract not more than 4%, the total stretch imparted to said filaments over said series of stretching and relaxing rollers being greater than the stretch imparted by the first of said stretching rollers.

References Cited in the file of this patent UNITED STATES PATENTS 1,968,912 Schrenk Aug. 7, 1934 2,346,696 Mority et a1. Apr. 18, 1944 2,599,603 Barker June 10, 1952 2,852,333 Cox et al Sept. 16, 1958 FOREIGN PATENTS 263,233 Switzerland Nov. 16, 1949 

1. A METHOD FOR MAKING HIGH TENACITY RAYON FILAMENTS WHICH COMPRISES EXTRUDING VISCOSE CONTAINING AT LEAST 0.5% OF A MODIFIER WHICH IS CAPABLE OF PRODUCING FILAMENTS HAVING A THICK SKIN, FROM SAID VISCOSE, INTO AN AQUEOUS ACID COAGULATING BATH TO FORM FILAMENTS, AND IMMEDIATELY STRETCHING THE FILAMENTS, WHILE THEY ARE STILL WET, IN A SERIES OF AT LEAST FIVE STRETCHING STEPS, THE FILAMENTS BEING STRETCHED FROM 4% TO 20% IN EACH STRETCHING STEP, THERE BEING A RELAXING STEP BETWEEN EACH OF SAID STRETCHING STEPS IN WHICH THE FILAMENTS ARE PERMITTED TO CONTRACT BY AN AMOUNT NOT EXCEEDING 4%, THE TOTAL STRETCH IMPARTED TO SAID FILAMENTS OVER SAID SERIES OF STRETCHING AND RELAXING STEPS BEING GREATER THAN THE STRETCH IMPARTED BY THE FIRST OF SAID STRETCHING STEPS. 